The double hyphen (＝, ゠, or ⸗) is a punctuation mark that consists of two parallel hyphens. It is not to be confused with two consecutive hyphens (--), which usually represents an em dash (—) or en dash (–). In order to avoid its being confused with the equal sign (=), the double hyphen is often sheared slightly.
The double hyphen is used for several different purposes throughout the world:
- Some typefaces, such as Fraktur, use the double hyphen as a graphical variant of the single hyphen.
- It may be also used for artistic or commercial purposes to achieve a distinctive visual effect. For example, the name of the Waldorf=Astoria Hotel is officially written with a double hyphen.
- In Merriam-Webster dictionaries if a word is divided at the end of the line, and the division-point happens to be a hyphen, it is replaced with a double hyphen to graphically indicate that the divided word is normally hyphenated, for example cross=
- In several dictionaries published in the late nineteenth and early twentieth centuries, all such compound words are linked with double hyphens, whether at the end of the line or not, and the normal use of the single hyphen for non-compound words is retained. An example from the first or second page of such dictionaries is Aaron's⸗rod. Examples include the Century Dictionary and Funk & Wagnalls New Standard Dictionary of the English Language.
- It is used as a distinct punctuation mark by Coptic language scholars.
- In Japan, the double hyphen is used as a separation for a person's name written in katakana, such as ジョージ゠W.゠ブッシュ (George W. Bush). However, a distinct double hyphen character is not supported in the main Japanese character encodings that are not Unicode, which are Shift-JIS for Windows and DOS, and EUC-JP for Unix and Unix-like systems. In practice, the equal sign, fullwidth equal sign, and, more commonly, the middle dot (・) are more frequently used instead. Another usage in modern Japanese is the replacement for hyphen, in order to avoid being confused with the prolonged sound mark, e.g. ウォルドルフ＝アストリア, or The Waldorf-Astoria.
When the double hyphen is used as a functionally equivalent graphical variant of the single hyphen, it is represented in Unicode as a normal hyphen.
When used as a punctuation mark distinct from the single hyphen, the double hyphen is represented in Unicode by two different code points:
|| Code point
|| Purpose |
| DOUBLE OBLIQUE HYPHEN
|| Western orthography (including Coptic language scholarship) |
| KATAKANA-HIRAGANA DOUBLE HYPHEN
|| Japanese orthography |